moving rock in trailer in cold climate

I will be transporting my reef, for the most part its just rock with alot of
decent life on more than half of them. i will be using a 20ft livein trailer
type and make a one way travel-journey up north from southern california
with a 60 gal reef that needs to run off inverters. 300 watt heater will
kill the bateries in no time. how cold can i let these things get? i can
reset the tank in washington for a few weeks, then its once more on its way
all the way north to alaska to even colder drives. i have a few crabs left,
a snail or two, a million small snails that i DONT want dead, small
starfish, only two yellow polpys left from greenhiir algae massacre,
mushroom that went from fully healthy to the size of a dime, and a very
small patch of pink stonys. i do have a few buckets with lids, would be
nice to put rocks in there with water and put lids on it and let them reach
60 degrees, this will kill them though right? so if this wont work then i
thought of a place where i could just transport the tank 1/3 full of water
with all rocks laying flat and heater on bottom with top of tank sealed for
splashing. trailer power will be good until overnight sleeps when truck
generator isnt charging batteries, the heater i cant see being on all night.
hmmm, i wonder propane heater underthe glass? heehee i could just see the
burnt sand spot in the middle now... (glass doesnt break when heated if
touching water, only if its cooled with cold water when hot.)
i also would like to take all of the live sand out and keep it in a bucket
and let it get 50-60degrees, or do i need to treat this stuff with more care
too? any help appreciated. thanks.
wolfhedd